Dusky sharkDUS

Carcharhinus obscurus

Carcharhinus obscurus ventral head
Carcharhinus Obscurus upper tooth

Characteristic features:

  • First dorsal-fin origin opposite pectoral-fin free rear tip
  • Second dorsal-fin inner margin long, its length 1.6–2.1 times its height
  • Interdorsal ridge present
  • Snout short and rounded
  • Upper teeth low, broadly triangular, erect to moderately oblique, edges serrated
  • Lower teeth narrow, upright, edges weakly serrated

Colour:

Dorsal surfaces bronzy grey to dark grey; a faint pale stripe on each side. Fin tips mostly dusky in juveniles, plain in adults. Ventral surfaces paler.

Size:

Maximum size up to 365 cm TL; birth size 69–100 cm TL.

Distribution:

Cosmopolitan but patchy, in tropical and warm temperate seas.

Habitat:

Found throughout the water column on coastal and continental shelves, but also seen well offshore following ships. Found from the surf zone to at least 400 meters depth.

Biology:

Feeds primarily on bony fish, sharks and rays, but also cetaceans, crustaceans and cephalopods. Length at maturity is at 295–310 and 265–280 cm TL for females and males respectively. Age at maturity is around 20–23 years and 17–22 years for females and males respectively. Reproductive mode is viviparous with yolk-sac placenta; females give birth to 3–14 (usually 5–12) pups, with Western Australian populations giving birth during summer and autumn after a 16 month gestation period; females breen every second or third year. Maximum age of the Western Australian population at least 32 years.

Indonesian fisheries:

Common component of the catch of the shark longline fishery. Utilised for its fins (very high value in larger individuals), meat, skin, jaws and cartilage.

Similar species:

Carcharhinus falciformis
Silky shark
Carcharhinus falciformis
Carcharhinus falciformis differs in having a first dorsal-fin origin well behind pectoral-fin rear tips (vs. in line with pectoral-fin rear tips) and a more narrowly rounded snout (vs. broadly rounded).

External links:

FishBase
The IUCN Red List of Threatened SpeciesTM